This invention relates generally to sensors for remote object detection and avoidance, associated for example with robotic systems, mobile security and inspection platforms, decoys, etc.
Presently known object detection systems include an array of multiple ultrasonic sensors fixed to a mobile platform or vehicle body. Each sensor is pulsed or driven to emit ultrasonic energy within a detection zone and reflected ultrasonic echoes are recorded and analyzed through microcomputers interfaced with the respective sensors through multiplexer electronics. While such systems are effective and successful to some degree, they are expensive to implement. Additionally, relatively expensive multiplexer electronics must be utilized to coordinate signal paths for proper analysis of all incoming reflection signals and timing data. Accordingly, such ultrasonic remote object detection systems of the type involving plural sensors fixedly mounted on a platform are severely limited in application by cost so as to be confined to laboratory use for test purposes as distinguished from widespread use in practical applications.
Movable scanning types of ultrasonic sensors have also been proposed for remote object detection systems as disclosed for example in U.S. Pat. No. 4,805,155 to Shiraishi et al. According to the Shiraishi et al patent, a sensor assembly is rotated in one direction on its platform by 360.degree. and consists of three separate transducer elements angularly spaced from each other by 120 degrees. In view of the noise generated as a result of the scanning displacement of the sensors associated with such systems, measures must be taken to compensate for noise signals injected into echo signals. The noise compensation measures, if successful to any acceptable degree, involve complex circuit modifications which sometimes render the movable scanning type sensor systems more costly than the platform fixed type of sensor systems aforementioned.
It is therefore an important object of the present invention to provide a low cost ultrasonic type of object detection system capable of performing its functions in a more effective, economical and reliable manner.
An additional object of the present invention in accordance with the foregoing object is to provide a remote object detection and avoidance system utilizing a movable scanning type of platform mounted ultrasonic sensor arrangement which avoids the noise problems and costly solutions usually associated therewith, which has heretofore limited application of such systems.